The Obama-Pelosi event...

President Barack Obama’s endless summer of fundraising is heating up — with the addition of a big-money August house party to help out House Speaker Nancy Pelosi’s imperiled Democrats, POLITICO has learned.

Obama plans to headline an Aug. 16 fundraiser for the Democratic Congressional Campaign Committee in Los Angeles — the first such appearance by the president on behalf of Pelosi since White House press secretary Robert Gibbs rankled House Democrats by suggesting they could lose their majority.

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The commitment to appear with Pelosi in LA — along with a signoff on an as-yet unscheduled Obama-DCCC fete — followed a White House meeting between Pelosi and Obama, according to Democratic insiders.

Obama’s ever-widening midterm fundraising offensive comes at a time when his approval numbers are at low ebb, with many Democratic candidates across the country more eager for his cash-raising efforts than his actual presence in their districts.

Mike Kelley, the former executive director of the Missouri Democratic Party, said Obama is “personally less toxic” than his abysmal 34 percent approval rating in the Show-Me State would indicate. Still, he said that Democratic Senate candidate Robin Carnahan “has probably seen enough of him this year” after a July 8 presidential visit that was taped by Republicans and turned into an ad.

“But that doesn’t mean [Obama] can’t be extremely helpful when it comes to fundraising,” he added.

Despite such headwinds, the president and his White House advisers — all battle-hardened 2008 campaign hands — are attacking the 2010 midterms with real verve, in part to buck up battered congressional Democrats, in part to road-test messages for Obama’s looming 2012 campaign, but ultimately because the commander in chief still gets a huge buzz from campaigning.

In fact, Obama was so fired up after a campaign event for Nevada Sen. Harry Reid in Las Vegas last month, he surprised the majority leader backstage with what amounted to a war whoop for Democrats in the midterms.

“They have been running a campaign for 18 months,” Obama said of congressional Republicans, according to a person who witnessed the exchange. “But they forget: We know how to win elections, too.”

Obama, according to a Democratic source, was so fired up after the Reid event, he sped back to his hotel for a beer and a poker game.

And if he can no longer count on the unalloyed adoration of huge crowds he enjoyed in 2008, he’s still the party’s biggest cash draw.

The LA fundraiser, which will take place at the home of Marilyn and John Wells, costs $2,500 per person to attend, although “co-hosts” will have to shell out as much $30,400 each, the maximum allowable contribution by a donor to a national party committee per year.

In a nod, perhaps, to Obama, no donations from registered lobbyists or lobbyists for foreign governments will be accepted for the event.

The West Coast swing is likely to include other events, only one of which has thus far been made public: a fundraiser for Washington Democratic Sen. Patty Murray, who is facing a daunting challenge from Republicans vying to challenge her.

Even as he hits the road, Obama’s internal ’10 team — led by senior adviser David Axelrod, chief of staff Rahm Emanuel and Emanuel deputy Jim Messina — are planning a slate of other fundraisers, which are likely to include fresh trips to New York and Florida to support candidates such as Senate hopeful Rep. Kendrick Meek.